Work clamp



March 19, 1963 o. F. CHRISTIANSEN WORK CLAMP Filed Jan. 2, 1962 FIG 3 'INVENTOR. OLE ECHRISTIANSEN l J TTORNEY 3,081,721 WORK CLAMP Ole F. Christiansen, Brookline, Mass, assignor to The Reece Corporation, Waltham, Mass, a corporation of Massachusetts Filed Jan. 2, 1962, Ser. No. 163,789 1 Claim. (Cl.112--235) This invention relates to work clamps for sewing machines and more particularly to a work clamp provided with means for preventing the trapping of the starting thread of a sewing machine.

In automatic sewing machines such as button hole sew ing machines, button sewers, and the like, it is necessary to provide an extra length of thread extending through the needle so that on the first stitch the free end of the thread will not be withdrawn from the needle. However, when this length of thread is provided, care must be taken, when placing the work under the clamp, to be sure that the thread will not be trapped under the clamp. Should the thread be trapped under the clamp, the needle on its first full stroke may break the thread, or, since the free end of the thread cannot be Withdrawn from under the clamp the required thread for the first stitch will have to come from the thread supply and will cause an excess length of thread to remain at the start of the line of stitches. In either case, this trapping of the thread will cause excess work for the operator. If the thread is broken the machine must be stopped, the needle rethreaded, and possibly the work repositioned before the operator can continue the sewing operation. If the thread does not break it may require a second person to trim these excess lengths of thread so that the sewing operation will appear presentable.

It is therefore an object of this invention to provide a work clamp which will eleminate the trapping of the starting end of the thread.

It is a further object of this invention to provide a work clamp which will receive and retain the free end of the thread as a previously finished work piece is removed from under the clamp.

A still further object of this invention is to provide a work clamp which is simple and cflicient in operation and economical to manufacture.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a top plan view of the work clamp forming the subject of this invention;

FIGURE 2 is a bottom plan view of the Work clamp forming the subject of this invention;

FIGURE 3 is a cross sectional side elevational view of the work clamp forming the subject of this invention; and,

FIGURE 4 is a perspective view of the work clamp forming the subject of this invention.

Referring now to the accompanying drawings, there is shown a work clamp, indicated generally at which is substantially rectangular in shape. The work clamp is formed of a base member 11 which is provided with a central aperture 12 extending vertically therethrough. The aperture '12 is bevelled upwardly and outwardly from the bottom of the base member to the top.

Extending upwardly from one end of the base 11 is a lug 14. The lug 14 has extending outwardly there from in a direction opposite the base 11 a bolt 16, or any other suitable means, by which the work clamp may be secured to the presser arm of the sewing machine. As seen more clearly in FIGURE 2, the bottom of the 3,081,721 Patented Mar. 19, 1963 ice base 11 is corrugated and is provided with a plurality of slots 18 which extend upwardly into the base and also extend from the aperture 12 to the outer wide edges of the base member 11. Extending circumferentially around the base member 11 on the sides thereof is a groove 20. The groove 20 is positioned substantially midway between the top and bottom surfaces of the base 11 and extends inwardly into the base member a distance substantially greater than the thickness of any thread which may be used therewith.

In operation, a piece of work is inserted in the machine and work clamp 19 is lowered whereby the work piece will be clamped between the work clamp and a base plate of the sewing machine, not shown. A needle 22 carrying a thread 24 reciprocates vertically through the aperture 12 thereby placing stitches in the work piece. After the stitching has been completed the work clamp is raised and the work piece is withdrawn from under the clamp. Upon completion of the stitching operation the thread from the needle is usually severed beneath the work piece by a cutter usually associated on these machines so that there is still some tension on the thread 24 due to its being imbedded in the work piece. As the work piece is withdrawn the thread 2-4 will follow whatever path is chosen for withdrawing the work piece. As the thread follows this path it will engage in one of the slots 18 in the base member and as the work piece is raised up the thread will pass all the way into one of the slots 18. As the work piece is further removed the thread 24 will be withdrawn therefrom and due to the twist in the thread will leave at an angle to its original path. This will cause the thread by its own natural inclinat-ion, to fall in the groove 20 wherein it will rest unless further disturbed.

When the next work piece is inserted in the machine the work clamp will be lowered to hold it in position. Inasmuch as the thread is held in the slots 18 and groove 20 it will not be trapped between the bottom surface of the base 11 and the work. As the needle descends on its first stroke it can freely withdraw the thread 24 from the groove 20 and slots 18 to the extent that it is necessary for forming the first stitch. Thus, the danger of breakage of the thread on the first stitch has been eliminated as well as the danger of providing too long a starting stitch which would require an excess operation to trim it. It will thus be apparent that the foot clamp of the present invention provides a normal and efficient manner of preventing trapping of the starting thread.

From the foregoing, the construction and operation of the device will be readily understood and further explanation is believed to be unnecessary. However since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the appended claim.

I claim:

A clamp foot for a sewing machine comprising a fiat base member,

an aperture in said base member extending vertically therethrough whereby a needle may pass through the base member to place stitches in a piece of work held by the base member,

an upstanding lug on said base member,

means on said lug for securing said lug to a presser bar forming part of the machine,

and means on said base member for receiving and retaining the loose end of a thread from the needle of the sewing machine,

said last named means including a plurality of slots in the bottom surface of said base member,

3 4 said slots extending between the edge of said aperture References (Jilted in the file of this patent and F outer edge said base UNITED STATES PATENTS and an inwardly extending groove in the side of sald base member extending completely therearound, 2,367,865 Hollander 1945 said groove being positioned adjacent the upper limits 5 2,445,629 Newton y 20, 1948 of said slots whereby the slots provide an entrance 2,476,161 sllverman y 1949 from the bottom of said base to said groove. 2,534,281 Luna 19, 1950 

